FILE – In this Sept. 18, 2013 file photo, Trader F. Hill Creekmore works on the floor of the New York Stock Exchange. Global stock markets fell Friday Sept. 20, 2013, two days after the Fed announced it would keep its unprecedented stimulus in place. Public holidays kept trading muted in Asia. (AP Photo/Richard Drew, File)

Washington’s budget fight jolted investors on Friday, reminding them that the next few weeks could bring a lot of uncertainty. Wall Street hates uncertainty.

Stocks fell in an afternoon sell-off that wiped out most of the gains from a rally earlier this week, when the Federal Reserve decided to keep its huge economic stimulus program intact.

Major indexes were mixed in morning trading, but turned lower around midday after the U.S. House of Representatives voted to defund President Barack Obama’s health care law.